The feds in Jersey are fuming that rogue real-estate mogul Charles Kushner is being transferred from prison to a cushy halfway house a year early – just because he claims to be an alcoholic.

Kushner, who retaliated against his own sister – a cooperating witness to his crimes – by hiring a prostitute to seduce her husband, hasn’t served even half of his two-year sentence, yet already this sweetheart deal will bring him closer to home and his real-estate empire.

According to The Star-Ledger of Newark, Kushner shaved time off by claiming to be an alcoholic so as to be eligible for a residential substance-abuse treatment program.

The program is the only one in the federal prison system that lets inmates earn credit against their sentences. According to the newspaper, the prosecution and the FBI are trying to prove that Kushner faked his way in.

They’ve interviewed liquor-store owners as well as his doctor and former employees of his to determine whether he perjured himself by claiming to be addicted.

At sentencing last March, the defense gave the judge hundreds of pages of documents and letters of support – yet none mentioned a drinking problem.

Yesterday, his lawyer, Benjamin Brafman, declined comment.

Kushner acknowledged setting up his brother-in-law with a call girl and having a tape of the tryst sent to his sister, Esther. The couple had been cooperating with a federal grand-jury probe into Kushner’s tax-fraud and campaign violations.